


Beyond the Sea

by madammina



Category: Kingdom Hearts
Genre: F/M, mermaid au
Language: English
Status: Completed
Published: 2019-10-08
Updated: 2019-10-08
Packaged: 2020-11-27 16:36:15
Rating: Teen And Up Audiences
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 1
Words: 4,015
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/20951534
Author URL: https://archiveofourown.org/users/madammina/pseuds/madammina
Summary: Aqua, a potential hero from the Greek city-state of Argos, is on a quest.  But during her sails, the wind refuses to blow and she and her crew get stuck.  Zack, a mermaid, finds them there.  This quick meeting grew into a story neither could have imagined.





	Beyond the Sea

**Author's Note:**

> This was for the KH Rare Pairs Zine! They are on both Twitter and Tumblr (which I don't know if I can link to) I had a lot of fun writing this. Please enjoy! And let me know what you think!

“I know it’s been two days, but we can wait a bit.” Captain Aqua said to her first mate Terra as she slammed her hand on the sea chart of the surrounding isles. Inside her cabin it was cool, and if she wasn’t busy debating how to continue her quest, she could hear the waves beat against the side of the boat. “Weather doesn’t always cooperate. If the wind doesn’t pick up by tonight we’ll start rowing with the stars.” 

Before Terra could respond, she swept out of her own captain’s quarters, with only her cape to provide any shade from the sun. After checking that Terra was still in the cabin, Cloud and Tifa were examining the rope, Sephiroth was reading, and Ven was busy in the galley. She went over to sit on the edge of the ship. 

“HI!” 

She looked down and saw someone swimming in the water. 

“Let me save you!” She gasped and began to get up before the voice said,

“Oh, I don’t need to be saved.” The voice said. She stood and waited for him to go on. “Well, I might eventually, but I’m fine right now. See?” The man the voice belonged to disappeared for a second, then jumped out of the water, revealing an elegant black fishtail with blue and silver highlights.

“... You’re a merman,” Aqua sighed. The man nodded. Aqua could see now that he had spiky black hair and bright blue eyes. “I’m Aqua.”

“That means water, from what I hear,” The man said. “I’m Zack.” 

“Nice to meet you, Zack,” Aqua said after a moment. “What are you doing here?” 

“Well, this IS my area,” Zack said. “Not much happens here, other than you getting stuck. What are YOU doing here in my part of the sea?” 

“Oh…” Aqua sat down again. “I’m on a hero’s quest. You see, I’ve been sent to find the fires that Prometheus brought to earth to prove that my home town should be the home for the Olympic games.” 

“Hmm,” Zack said. “Is that what heroes do, seek glory? I thought they helped people.“

“Many times,” Aqua admitted. “Other times they are sent on missions by the gods or their states.”

Zack frowned as he thought about this. Suddenly a thought struck him and he looked up. “What are you doing here though? Shouldn’t you be on some land-based island?” 

“Wind won’t blow,” Aqua replied. “Normally people offer a sacrifice to Poseidon to get the sea moving, but I’m from Argos and our patron deity is Hera. Hera, she -” Aqua paused. 

“Wouldn’t take kindly to a sacrifice for someone else?” Zack offered. Aqua nodded. 

“Yes. She may be the Queen of Olympus and patron of marriages but the sea isn’t her domain, and if I try to appease Poseidon she will make life VERY DIFFICULT for me and my crew.” Aqua sighed. 

“Why are you doing this?” Zack asked. As he asked he pulled himself up on a nearby rock so he could lay there and look at Aqua more eye to eye. “Not to get the fire. Why are you, Captain Aqua, doing this?” 

“... I want to be a hero.” She said after a moment. “Someone… someone who’s worthy of things. Who people can look up to, who can do anything that is asked of them. They are people who have earned the respect and trust of the people and I think if I can be a hero… it doesn’t matter what I do with my life. I must do it for other people. Everyone needs a hero, why not me. I can help people that way.” 

Zack seemed to pause a second, flashed a smile, then opened his arms. “I CALL UPON THE FATHER OF THE SEAS, POSEIDON-”

“Zack-” Aqua hissed. “What are you doing?” 

“Please, I call upon your benevolence to help Aqua of Argos who wishes not to anger her patron but also acknowledges your supremacy over the sea. Help her in the quest to find what she seeks!” 

Instantly, the ship began to move. Terra ran out of the cabin onto the deck and she could hear Tifa cheering. Zack smiled as Aqua called out, “Thank you!” 

“You owe me!” He called back. Aqua laughed, thinking that they were probably never going to see each other again.   
***  
They met again two weeks later. 

“How goes the fire searching, Captain Aqua!” A voice called from the side of the ship. Aqua stepped away from the map, Terra followed her, and they both went over to the side of the ship. Keeping up with the ship was a merman with black hair and a black tail. The sea glimmered bright blue as the dark form bobbed up and down next to the hull. Inside the Galley, Aqua could hear Ven singing but soon tuned him out to look at their new visitor.

“Hello, Zack,” She replied. “OH! First mate Terra, please meet the Mermaid Zack. Zack, this is my first mate! Terra, Zack is the one who called upon Poseidon on our last trip.” Terra decided to wave at Zack, who cheerfully waved back. 

“And how did that go?” Zack asked. 

“We found the fire once you helped us, now we are off to capture Harpies!” Aqua explained as Terra left the two of them alone. 

“Oh, that sounds… like something,” Zack said. “Have you become an adventure of renown yet?” 

“A HERO. And no… not yet,’ Aqua sat down on the ship. “It’s a process. It took Odysseus years to come home after all.” She frowned, “I get to go home, at least.” 

“Is Argos your home?” Zack asked. 

“Yes, but you ask me questions all the time, Zack!” She smiled. “Tell me something about you!” 

“Well, I’m a merman. That’s easy enough to figure out though.” He said. “I’m not the only one, obviously. We all live underwater in these BIG cities! I have… let’s see… 15 brothers and 20 sisters…” 

“That’s a lot,” Aqua replied. 

“Well, mermaids, eggs, you know how it is.” He seemed to shrug. “We spend a lot of time worshipping Poseidon. We’re all his something great grandkids you see. He spoils us by lettings us swim forever.“

“... That really does sound great.” Aqua admitted. “But what are you doing up here?” 

“Oh, I like seeing people sometimes,” Zack replied. “Can you tell me a story? About a hero you admire?” 

“Hmm… shall I tell you of Odysseus and his forty years to get home, or of Jason and the Argonauts?” Aqua asked as she pulled out some sail cloth and prepared to fix it. Stories always worked best when you were doing something. 

“Odysseus!” Zack said. “You can tell it to me in parts, in case we get separated so I have a reason to find you again!”

“Fine,” Aqua said. “But you have to tell me a story too.” 

***  
“Hey, Hey, Aqua. Come into the water… come in… it’s so lovely you will never ever ever want to leave…” Zack said in a spooky voice. Night had fallen on the ship as their next adventure called them back out to sea. Tifa was steering the ship, but other than that, it was just Aqua who had volunteered to take watch. 

Upon hearing the now familiar voice, Aqua responded by dumping the scraps from dinner on top of him. “No.”

“THAT’S LITTERING!” Zack replied. “But I do want you to come in! It’s tiring keeping up with you all the time.” He paused. “Plus I get distracted when you tell me stories.” 

“It’s not intentional, Zack.” 

“Yeah, but… look you sound like you have an interesting life and I only get to see part of it!” Zack pleaded. “And I can’t go on the ship without the risk of drying out. So come into the water!”

“Can’t you meet me on a dock?” Aqua asked. “There has to be islands around here where we can meet.” 

“They don’t like mermaids at the surrounding islands,” Zack sighed. He somehow flopped on the water, with his arms out. “You’re lucky, you get to go anywhere.”

“You’re lucky, you get to go under the sea,” Aqua replied. “Do you have any jobs or duties under the sea?”

“Kinda?” Zack tilted his head. “Not like you, the Hero.”

“Heroine in training,” Aqua said. “I just go to wherever a monster needs to be slain or a person saved.” She sighed and rested her head in her hands. “You?”

“Farmer,” Zack said. “Kinda. It’s stuff like kelp and mussels. They mostly take care of themselves.” He appeared to shrug. “COME SWIM WITH ME PLEASE!” He said as a wind came and pulled Aqua’s ship away. Aqua laughed, and she could hear Zack laughing too.

***  
“What if… what if I wasn’t a merman,” Zack said on the next trip. Aqua had the night shift and Zack let himself be pulled up onto the deck… as long he stayed in an old barrel of seawater. “What if I was secretly a SIREN. Or your cook Ven was a siren who just used you to look for victims!” He paused. “What would a siren call for you to get you to drown?” 

Aqua paused, a skewer of fish and grilled vegetables partway to her mouth. “Can a siren call for respect?” She asked before giving Zack some bread she had set aside for him. He tore into it. 

“OOH. This is warm,” He said. “And maybe? I think my great aunt is a siren, but I haven’t seen her for some time. How do you MAKE this thing?” 

“In an oven,” Aqua replied. “I guess offering honor is a bit hard for a siren. They may lure you in with what you want, but they have to be able to prove it, I guess.” 

“I know what I’d get if I siren tried to get me,” Zack said confidently as he ate more bread. “A pet.” 

“Don’t talk with your mouth full,” Aqua replied, then went back to her own meal.  
***  
A month later, Aqua and Zack reunited on a beach. Well, they had to keep partly in the water, but for once Aqua could lay on the sand and actually talk to Zack. 

“I’m serious. I want a dog like that.” Zack was saying as he pointed at a dog that went by on the beach. Aqua was partly in the water today. And she had a whole day off, as her ship needed to be in for repairs after that last storm that a Kraken had created. Zack was next to her, sand up to his waist to hide his tail. “We don’t really have pets underwater.” 

“I thought you would have pet fish,” Aqua said. She handed Zack a fresh loaf of bread that Ven had made just for Zack and he began to tear into it. This time he swallowed before he spoke again. 

“They… they don’t do much. You can train dolphins as pets though,” Zack said. “And they are great, but they need a lot of space so they can be a hassle. And slightly territorial.” 

“Dogs aren’t that bad, but they can be kind of dumb,” Aqua explained. The sun shimmered on the water and she lay back a bit until she hit the sand. It got into her hair as she closed her eyes and tilted her face towards the sun. “I like the sun,” She finally said. “The light that makes the world grow.” 

“Hmm…” Zack attempted to mimic her gesture, but as he needed to keep his tail hidden, the best he could do was lay on his elbows. “I can see that, but it’s so dark under the sea. I was born into it so I can live there, but sometimes this world… it seems so bright it hurts. It’s fine for a while, but everything is laid bare, and you can get hurt. When the dark is comfortable, you feel safe. Things can grow in the dark. At least our things.” 

“... I can see that,” Aqua said after a moment. 

“Are you a hero yet?” Zack asked after a moment. 

“Not yet,” Aqua said. “I think most heroes die in glorious battle.”

“Odysseus didn’t,” Zack replied. “There have to be others.” 

“If there are, there aren’t that many. Odysseus was very well-liked by Athena.”

“And you have Hera.”

“And I have Hera,” Aqua paused for a second to feel the waves gently hit her legs. “Again, to clarify, she REALLY helps those who like her and serve her… but she is really hard to impress.” 

“I think you can be a hero without dying,” Zack said as he began to slide deeper into the water. Aqua got closer to him and gently took his hand. 

It was cold, then again he was part fish. But Aqua could feel his heartbeat, and he had such a kind heart. 

Aqua squeezed his hand, and he squeezed back. 

***  
“Tell me something positive about your world,” Zack said the next time they were on an island. Her crew had decided to stay on this undiscovered beach for the day in order to do some fishing. Terra had the patience, but Tifa had a kind of sixth sense when it came to fishing. Ven was waiting to prepare the dinner, Sephiroth had set up some kind of training course using the trees, and Cloud was being harassed by dolphins. Before Aqua had found Zack, Cloud had fled the water in order to hide up on the shore by Ven.

“And not sun related?” Aqua guessed. Zack shrugged and laid back down on the sand this time. Most of the crew had stopped caring that he swam beside the ship a while ago. 

“I just want to know why you like it here,” He said. “Why is being a hero for this world so important?” 

“Someone has to do it,” Aqua said after a moment. “There are people who can’t defend themselves. I want them to be safe. People can be good. And even if they aren’t, there’s always stuff like seeing the season change, or dogs, or plants growing, or someone you love cooking your favorite food.” 

Zack paused.

“Do you have someone you love?” He asked. 

“My mom and dad,” She said without missing a beat. “They’re fishers in Argos.” 

“Oh!” Zack smiled. “Are you wanting to be a hero for them?”

“A bit,” She said softly. “Someone needs to protect people like them.”

“People like what?” Zack asked. 

“People who… who need help.’ She admitted. “I know it sounds circular, but someone has to defend them. Everyone has their place, mine is to try to defend people and hope that’s a good thing.” 

***  
“I’m scared about this next adventure, Zack. We could even go past the end of the world.” Aqua said, her legs in the water as she sat on the dock. 

“Are your parents okay?” Zack asked as he tried to pull himself up on the dock. “I know you said they are probably fine but you seem like you could be gone for a while.” 

“So far…” Aqua trailed off and put her chin in her hand. As she watched, the sun set and stars began to litter the sky. 

“The one thing we don’t really get under the sea is stars,” Zack said softly. “You are lucky for that.” 

“With stars,” Aqua said softly. “You always know where you are.” 

***

“We don’t have stars, but we have other things,” Zack said one night. Sephiroth was off sulking at the helm over not being able to kill the latest monster. Aqua was the only other person on deck, and she was busy patching up some of the extra sailcloth. 

“Like what?” She asked. “We have hot food here.”

“True,” Zack admitted. “But you guys are always fighting. Mermaids are a lot more… craft-focused,” He said after a second. “We like to sew and learn and do research. Scientists and mages and philosophers are the most respected down there,” Zack said. “And with everything being dark, we have a lot of things that glow.” He glanced back at the stars, “ The stars are nice, don’t get me wrong, but seaweed that glows green so you can find your path? It’s so amazing. And we don’t have the same seasons as you, but the sea always changes things, and there is so much to explore!” 

“It does sound great, Zack,” Aqua said as she looked at the sailcloth. A Hydra had cut it in their last fight. Terra was still recovering from some hearing loss. “I wonder what it would be like to be a hero without fighting?”

“Or dying.” Zack reminded her. “You can be a hero without that. After all, a hero is just one that helps, right?” 

***  
Aqua ran out onto the deck of the ship. Something was wrong. She could tell. Ven had stopped singing. As she ran out, she found Zack tied up in a net on deck. Blue blood was coming from a gash on his chest as he seemed to shrivel up under the sun. As she walked towards Sephiroth, she tripped over something soft. As she pushed herself up from the deck, she looked to the side. 

Terra was splayed out, a net cast over him so he couldn’t move. 

She could see he was breathing, so she staggered up, and looked around. Cloud and Tifa were together on one side. They were holding hands and had matching holes in their chests. Both seemed to be breathing too, but they couldn’t do much else. Tifa was staring at Sephiroth, vengeance in her eyes. Ven was out too, pinned to the deck by something sharp. He wasn’t unconscious, but he couldn’t move either. 

“SEPHIROTH!” Aqua shouted as she pulled out her sword. “What happened? Why are my crew pinned like this? What did you do?” 

“Why do you want to be a hero, Captain?” Sephiroth asked as he turned towards Aqua, “Is it for glory? Honor? Respect?” 

“To do the right thing!” She shouted back, as she pulled her sword out. “Why are my crew like this?” She asked. Zack was gasping, but she couldn’t run to him without running past Sephiroth. Sephiroth stood straight, his sword dripping blood. 

“They stood in the way of my glory. Sacrifice the mermaid, and I will fight Poseidon to gain glory as the god killer.” Sephiroth explained. “Kill Poisiden, become a hero. Isn’t that how this works? The monsters we have killed over my time serving under you, it has led to this.” He turned back towards Zack and lifted his sword, “So just be quiet, and I’ll let you share my glory.” 

Aqua tensed, and ran across the ship, her sword out. Sephiroth turned and managed to block the blade. Aqua, however, shoulder tackled him, and Sephiroth sprawled on the deck. She turned and ran toward Zack, half tripping, and pulled a knife from out of her belt. She began to saw at the net, as Zack looked up at her, his hair and eyes turning white. 

“Hey,” he said softly. “At least you get to be a hero here.” 

“Stop talking,” Aqua snapped. “No heroics are worth your life.” 

“Your crew tried to stop him,” Zack said. “They all seemed nice. Aqua…” he paused and reached out his hand, “Thank you.”

“Zack!” Aqua shouted, and began to saw faster. She could hear something moving behind her, probably Sephiroth, but before Sephiroth started moving, something flew through the air and landed on the deck with a THUD.

“I got him.” Terra hissed. “Get Zack and go!” 

“But-” Aqua looked back. Sephiroth was tangled in the net that Terra had thrown. Ven was twitching too, and even Cloud and Tifa looked like they had moved slightly. Aqua took in the sight and went back to Zack. But in that second, she realized Zack’s hand had fallen. “Zack? ZACK!”

Water spouted from the sea and turned into a hand. Aqua ignored it, and with a few more sawing motions, the net opened. Zack’s body tumbled to the deck, his skin flaky, and his hair pure white. Aqua held him to her chest, as the hand slammed onto the deck, and grabbed Sephiroth. She could barely even notice the rainbow-like spray across the deck, and the human form appearing in it. 

Instead, she held tight to Zack and sobbed into his hair as the water hand reached and pulled Sephiroth down into the depths. 

“Oh dear.” A new voice said. “My most devoted hero can’t be seen like this.” 

The most beautiful grandmother Aqua had ever seen stepped out of the rainbow. She waved her hands and Aqua’s other crew began to move slightly. 

“Unfortunately, while I can help the humans of your crew-” Hera said - it had to be her - as she knelt down by Zack’s body. “I can’t do the same for the one you love.”

“I-” Aqua swallowed the words in her mouth. “I don’t love him” was a lie. Seeing him was something she looked forward to every trip she took. 

“Save him,” Was what she whispered instead. Hera shook her head. The deck creaked and Aqua realized someone else had arrived. A man, tall and strong with blue hair. 

“That is my job,” Poseidon - was it him? - said. “You who have protected my child, who has shown nothing but respect for my sea, I can grant the boon to heal him. However-” Poseidon paused, “These come at a cost.” 

“We are gods, we do nothing for free.” Hera chimed in. “Though I have a boon of my own to grant, for all that you have done in my name.” 

“Master Poseidon,” Terra limped over, and then fell to his knee. “Do not request this of my ship’s captain. Let me pay for the boon instead. Zack has been good to have on these voyages, and I do not want to see him separated from my captain.” 

“Oh Terra,” Aqua whispered. “I can’t let you do this.” 

“To give his life,” Poseidon said as he sat down in front of Aqua. “Your life must be given up instead.” 

***  
Zack woke up on a partially submerged sandbar. Aqua’s ship was nearby, he could see Terra, Ven, Cloud, and Tifa working on it. He groaned as he sat up, water lapping at his waist. For a second, he thought he saw he had legs like Aqua, but no… still fins. 

Aqua.

“AQUA!” He shouted, pushing himself up as high as he could go. “AQUA! Where are you? Are you okay?” 

“Zack!” A voice popped up from deeper in the sea. As Zack watched, Aqua swam awkwardly over to him. Soon it became clear why she wasn’t moving that quickly. 

She had a mermaid tail, sparkling blue and silver. 

“Zack! You’re alive!” Aqua said as she wrapped her arms around him. 

“I could say the same thing about you!” Zack said. “What happened? Why are you a mermaid?”

“I had to give up my human life to save you,” Aqua explained. “I can’t be recognized as a hero, but it’s okay! You’re safe and alive!” 

“... Aqua,” Zack blinked away tears, and then put his head on her shoulder. “I should have told you this before. You’re a hero to me. I love you.”

“I love you too,” Aqua whispered back.

“FINALLY!” A new voice said behind them. Zack managed to turn around, once he let go of Aqua, and found an older woman there with a peacock. “I can now bless your marriage. Once you get married, of course. If you want it now.” 

“... LADY HERA?” Zack said. “Of Argos?” 

“I did promise a boon, not that my hero knew what it was,” Hera admitted. “If you wish to get married, I can bring Aqua’s parents over here and you can be married in front of them, and Poseidon, and her crew.” Hera gave a wink, “It’s up to you though.” 

Zack paused and put his hand in Aqua’s. He smiled at her, a smile she returned.

“Yes,” Zack whispered. “I do.”


End file.
